Heat exchanger



Filed March '7, 1940 ATTORNE Patented Aug. 26, 1941 amass nns'rnxcnsncan. Carl s. need. New York, N. 1., mm to The Lummus tion ofDelaware many, New York, N. Y., a corpora- Application March '1, 1940,Serial No. 322,652

ICIaim.

This invention relates to improvements in heat exchangers moreparticularly of the shell and tube type and specifically relates to theconstruction of the floating tube sheet and cover therefor.

It has heretofore been proposed to provide a detachable cover for thefloating tube sheet of a shell and tube type heat exchanger so thatthetubes can be exposed for cleaning and inspection, and it has also beenproposed that the cover be attached in such a manner that the tube sheetcan be removed from the shell of the exchanger without requiring aninordinately large shell. In addition to the need of a detachable cover,which could be readily removed, and attaching means of such a type thatthe tube sheet could be withdrawn or inserted in the tube bundie, it isessential that the cover be secured in a tight manner not only when theconstruction is originally assembled, but so that it will remain tighteven after extreme changes of temperature and pressure.

In the copending applications of Jacocks, Ser. No. 277,812, filed June"I, 1939, and Gibb, Ser. No. 294,797, filed Sept. 14, 1939, which onNov. 26, 1940, issued, as Patent Nos. 2,223,319 and 2,223,318,respectively, it has been found most effective to provide a continuousembracing ring surrounding the cover and the tube sheet, such ringpreferably being 'of inverted L-shape in cross section with thehold-down devices project- Q ing through the overlapping flange toengage the cover directly and immediately above the gasket. Theembracing leg portion of the ring was secured to'the tube sheet in theparticular manner specified in such applications.

Such constructions are of particular advantage in that with thecontinuous ring there are i no unreacted moments brought about by theeccentric loading of the hold-down members, and the diameter of thecover and tube sheet can be a minimum. The thickness of the embracingringwasnominalasitwasplaced entirelyin tension and it need be only of aminimum length to assure an adequate connection in shear with the tubesheet.

In accordance with a preferred form of embodiment'of my invention,modifications have been made in the manner of attaching the continuousembracing ring to the tube sheet in. order to reduce the cost, expeditethe attachment and accomplish a secure connection. In particular, thepresent invention has for its principal object, the provision of afloating cover attachmenttothefloatingtubesheetofaahelland tube typeheat exchanger by the use of a continuous embracing ring enveloping theperipheries of the cover and tube sheet and being anchored to the tubesheet by a detachable split key.

More specifically, the present invention includes the provision of asplit key for the purpose hereinbefore set forth, which engages underthe tube sheet and is embraced by the tube sheet on two sides so thatduring the initial setting up of the apparatus the split key is held inthe determined position.

Further objects and advantages of the invention will appear from thefollowing description of the preferred form of embodiment thereof takenin connection with the attached drawing, inwhich 1 is a vertical centralsection through a part of the heat exchanger showing the manner ofattaching the cover to the floating tube sheet;

Fig. 2 is a vertical section taken substantially along the line 2-2 ofFig. 1 and being broken away in part to show the manner of attaching thekeys;

Hg. 3 is a sectional detail showing the disassembled construction of theretaining ring and parts shown in Fig. 1.

In accordance with a preferred form of embodiment of my invention, asmore particularly shown in Figs. 1, 2 and 3, the heat exchanger is ofthe shell and tube type, the outer wall III of which is normallycylindrical and isprovided with suitable flanges II to which the shellcover I! may be secured through its flanges II. Within such shell is atube bundle consisting of a plurality of tubes ll which terminate in atube sheet ll generally known as a floating tube sheet in that it isfree to expand and contract from the opposite end or flxed tube sheet,not herein indicated. The construction of such heat ex changers is suchthat the floating tube sheet II is necessarily of smaller diameter thanthe shell ll so that the tube bundle 'may be inserted from the oppositeend in the desired manner. It is also well known and important that therelative dilference in diameter between the diameter of the'outer tubesof the tube bundle and the inner diameter of the shell be a minimum, notonly toreduce cost but to improve the efficiency of the heat exchanger.

In order to transfer the fluids flowing through the tubes from one groupof the tubes to another, it is common to provide-some form of covergenerally indicated at H and being known as the floating tube sheetcover. This embraces the tube sheet and serves as a channel, and, ifdesired, may be provided with an internal baiiie Ila which, in thepresent case, provides for a four-pass construction on the tube side.

My invention is more particularly related to the manner of attachingthese covers 11 to the floating tube sheet I5. The preferredconstruction includes a continuous ring which is pre- Ierably L-shape incross section in that it is provided with an offset flange portion 20awhich is provided with holes suitably screw threaded to receive theadjustable members 22 which contact directly with a boss on the coverIT. This is preferably as nearly in line with the gasket 24 contactingwith the tube sheet as is possible to assure direct loading. Thecontinuous member 20 is also provided with an extended embracing portion20b which embraces the periphery of the cover l1 and the periphery ofthe tube sheet l5. In addition, it projects across the tube sheet and,as shown in Fig. 3, is provided with a recess 200 which is adapted toreceive a retaining ring means 25 by which it can be secured to the tubesheet Ii.

The retaining means 25 includes a plurality of split members generallyindicated at 25a, 25b, 25c, and 25d in Fig. 2. Split rings of this typeare readily assembled and can be readily disengaged so that the partscan be promptly assembled and disassembled. The split ring portions arealso provided with a recess on the tube sheet side, which recess isindicated at 21 and, as shown in Fig. 1, is such that the tube sheetwill embrace the retaining means on two faces, including the axiallyextending face which, as shown in Fig. 1, tends to hold the retainingrings in position in the recess 20c and a transverse face which servesas the abutment. The ring portions may also be provided with a chamferededge indicated at 29 which will serve to establish an interlocking gripwith the base of the recess 200 which may be oppositely cut at 28. Whenthe load is applied through the adjustable bolts 22, the ring portions25 will then be firmly anchored against the tube sheet and embracingring, and dislodgment will be rendered almost impossible.

It will be aparent that with such a construction application of a loadon the bolt 22 will apply a satisfactory compression on the gasket 24and will anchor the cover with the desired uniformity and security. Theload reaction is directly taken up by the leg 20b of the continuous ring20 which, being in direct tension with a minimum of offset forces, willremain tight irrespective of pressure and temperature changes.Furthermore, the adjustable bolts 22 are in compression and there is nomaterial differential in length which would tend to loosen the Joint asthe temperature increases.

"I he construction is also particularly helpful in e,254,1se

the assembly of the cover as it is possible to slip the segments of theretaining rings into posi tion and as the continuous ring 20b is pushedinto place, the ring members 25 will be held in the desired position.With heavy construction characteristic of heat exchangers, this is ofespecial benefit.

It will be appreciated that the use of a connection of this type forsecuring the cover to the floating tube sheet will make it possible touse the minimum size of shell for the maximum diameter of tubes, as theclearance required for the relatively thin continuous ring 20 isinsignificant, The overall length of the continuous ring 20 is notexcessive and does not require materially greater costs in theconstruction of the shell cover, and such costs are more than offset bythe simplicity of the construction and the relatively low expense ofmachining.

While I have shown a preferred form of embodiment of my invention, I amaware that modifications may be made thereto and, therefore, I desire abroad interpretation of my invention within the scope and spirit of thedescription herein and of the claim appended hereinafter.

I claim:

In a heat exchanger of the class described having a shell, a tube bundletherein including a tube sheet removable through said shell, and a coverfor said tube sheet, the combination of means to secure said cover tosaid tube sheet, said cover being of substantially the same diameter asthe tube sheet, said securing means including an in dependent continuousring member having a skirt portion embracing the peripheries of thecover and the tube sheet and having an integral flange portion overlyingtne top of the cover, adjustable members in compression carried by saidflange portion and engaging the top of the cover, said skirt portionbeing substantially cylindrical and relatively thin-walled and extendingbeyond the tube sheet, said skirt portion having a peripheral channel inthe internal wall of the extended portion, and a split ring-extendinginto said recess and detachable therefrom, said split ring projectingradially inwardly to engage the tube sheet on the side opposite thecover, whereby on adjustment of the adjustable members the split ringwill anchor the continuous ring member to the tube sheet to resist theapplication of pressure on the cover with respect to the tube sheet, theperipheral channel in the continuous ring being inwardly recessed on itsedge remote from the tube sheet, and the split ring being inwardlychamfered on the adjacent edge whereby the split ring will beinterlocked on its edge remote from the tube sheet with the continuousring on the ap plication of sealing pressure on the cover.

CARL S. REED.

